Core-Shell Nanoparticle Generation

Using Laser Ablation

Vanessa Coronado, Westside High School, Houston ISD

Dr. Sy-Bor Wen/ Assistant Professor and YoungKyong Jo/ Ph.D. student Dept. of Mechanical Engineering

http://www.istm.cnr.it/~ponti/NJC06.html

Dr. Sy-Bor Wen, Department of Mechanical Engineering

• Ph.D. in Mechanical Engineering

@ University of California at Berkeley, CA

• M.S. and B.S. in Mechanical Engineering

@ National Taiwan University, Taipei, Taiwan

• Working on using lasers to ablate germanium and copper and condense them together to form a nanoparticle core-shell material that has superior optical and electromagnetic properties.

• Uses 2 lasers to ablate a germanium and copper sample a fraction of a second apart

• The second material (copper) condenses onto first (germanium) to form core-shell particle

• Particles deposit over time and are sent to a SEM and/or a TEM for imaging

• If the particle is a core-shell particle…party…. then determine the properties of it.

If you will recall, our project….

What could my class do to cover the TEKS and touch on some of the cool stuff we’ve done in the

laboratory?

• Using lasers

• Creation of nanoparticles

• Experimental design

• Energy conversions and thermal expansion

The main ideas that our research project touched on were:

So, after MUCH deliberation….

I decided to use laser light and having the students design a project!

Why?-Most realistic costs- after many hours pricing

items from internet-Most concepts for kids to learn within the

physics TEKS-Topic with the most design ideas

Physics TEKS Project Will Cover:

(8)  Science concepts. The student knows the characteristics and behavior of waves. The student is expected to:

• (A)  examine and describe a variety of waves propagated in various types of media and describe wave characteristics such as velocity, frequency, amplitude, and behaviors such as reflection, refraction, and interference;

• (B)  identify the characteristics and behaviors of sound and electromagnetic waves; and

• (C)  interpret the role of wave characteristics and behaviors found in medicinal and industrial applications.

Or, the recently revised Physics TEKS:(7) Science concepts. The student knows the characteristics and

behavior of waves. The student is expected to: • (A) examine and describe oscillatory motion and wave

propagation in various types of media; • (B) investigate and analyze characteristics of waves, including

velocity, frequency, amplitude, and wavelength, and calculate using the relationship between wave speed, frequency, and wavelength;

• (C) compare characteristics and behaviors of transverse waves, including electromagnetic waves and the electromagnetic spectrum, and characteristics and behaviors of longitudinal waves, including sound waves;

• (D) investigate behaviors of waves, including reflection, refraction, diffraction, interference, resonance, and the Doppler effect;

• (E) describe and predict image formation as a consequence of reflection from a plane mirror and refraction through a thin convex lens; and

• (F) describe the role of wave characteristics and behaviors in medical and industrial applications.

Focused L.A.S.E.R.s are used in….(AKA “Mrs....why are we doing this?”)

Besides the fact that it’s cool:• DVD and CD players• LASIK eye surgery• Metal working• Etching• Weaponry• Microscopes• Alignment• Ablation• And much, much more!

Safety First!

• Today, it is accepted that even low-power lasers with only a few milliwatts of output power can be hazardous to human eyesight, when the beam from such a laser hits the eye directly or after reflection from a shiny surface. At wavelengths which the cornea and the lens can focus well, the coherence and low divergence of laser light means that it can be focused by the eye into an extremely small spot on the retina, resulting in localized burning and permanent damage in seconds or even less time.

• Students will be signing a safety contract designed for this project. (Even though our lasers aren’t high powered.)

http://en.wikipedia.org/wiki/Laser

What will the kids be doing?

Their project sheet states the following:

*tentative

What will we be using?· A 7 beam laser box (have ordered 2)

· A light meter -measures lux (ordered 1 so far) -possibly probeware, depending on what the school can do.

We will also be using….

6+ Mirrors 6+ Lenses

...different shapes and sizes of mirrors/lenses for purpose of discovering which works best for their challenge activity

http://www.surplusshed.com/pages/item/l1875d.htmlhttp://www.christianbook.com/Christian/Books/oversize?sku=754037

How will they be scored?

Example project

This project has 4 segments, the beam covers 177.5 cm (1.775m) and has 33% of the original intensity.

1 (57.5”)

2 (52.5”)

3 (34.2”)4 (33.3”)

How would I calculate my score?

S = N * L * (I)2

n (i)2

S = 4.0 *1.775m*(.33)2

1 ( 1 )2

S = 4.0 *1.775 *0.11 = 0.78

I bet they can do much better than this!

Other scores obtained on mission:• Schematic Drawing

You will need to draw a schematic of your design that is to scale. You may pick the scale (1:2, 1:10, 1:50, etc). When you draw a schematic, you should include as many dimensions as possible to give NASA an idea of how to duplicate your project. See classroom example and rubric for help.

• Team Interview and PresentationYou will need to know about all parts of your project for a brief presentation and team interview. You will explain how your project is solving the problem. The interview is very brief, and consists of “why” and “how” type questions.

• Journal of Design ProcessYou will need to keep a ledger of your design process, good/bad ideas our group had, who did what, etc. The more detail you include, the better your grade- so be thorough. You will also answer some questions given in class here as well.

Pre-Test/Post-Test

Pre-Test/Post-Test

Project Timeline

• Day 1: Pre-Test ~25 minSafety Lesson ~ 10 minQ: difference between sci. & engr.? ~10 min

• Day 2: Engineering design lesson ~20 minAssign project and groups of 3-4 ~20 minJournaling questions ~ 10 min

• Day 3: Vocabulary and demos ~15 min Student design time ~30 min

During warm-ups and class time- journaling will occur.

Project Timeline• Day 4: Student ocular discovery activity online ~15 min

http://www.glencoe.com/sites/common_assets/science/virtual_labs/E11/E11.html

Student design time with supplies ~30 min

• Day 5: Trials and redesign ~45 min

• Day 6: Final test and calculations ~45 min

• Day 7: Present projects ~5 min each group x 10

• Day 8: Post-Test ~25 min (catch-up time if needed ~20 min)

*During warm-ups and class time- journaling will occur.

Journaling (Interactive Notebook)

• Inventors, engineers, naturalists, and scientists all keep written records of their work!

What is difference between science and

engineering?

Class info, notes, etc.

Engineering design flowchart

Results and discoveries

Vocabulary, concept maps

Targets “type B” kids

Any Questions?

Acknowledgements

• Texas A&M

• National Science Foundation

• E3 RET Program coordinators

• Mechanical Engineering Dept

• Dr Sy-Bor Wen and his team

• And viewers like you